Remove some ASSERT (and cast) in favor of checked cases.

Because it is a stronger pattern at runtime.
These were found by essentially:  grep -ni '\bassert\b.*type'

Change-Id: I913d77139053e8980528597a6633e1859e5204c4
Reviewed-on: https://pdfium-review.googlesource.com/38890
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

3 files changed, 114 insertions, 74 deletions

diff --git a/core/fpdfapi/cmaps/fpdf_cmaps.cpp b/core/fpdfapi/cmaps/fpdf_cmaps.cpp
index ad1091910c..630942bde7 100644
--- a/core/fpdfapi/cmaps/fpdf_cmaps.cpp
+++ b/core/fpdfapi/cmaps/fpdf_cmaps.cpp
@@ -74,31 +74,40 @@ uint16_t FPDFAPI_CIDFromCharCode(const FXCMAP_CMap* pMap, uint32_t charcode) {
     return 0;
   }
 
-  while (pMap) {
-    if (!pMap->m_pWordMap)
-      return 0;
-    if (pMap->m_WordMapType == FXCMAP_CMap::Single) {
-      const auto* begin = reinterpret_cast<const SingleCmap*>(pMap->m_pWordMap);
-      const auto* end = begin + pMap->m_WordCount;
-      const auto* found = std::lower_bound(
-          begin, end, loword, [](const SingleCmap& element, uint16_t code) {
-            return element.code < code;
-          });
-      if (found != end && found->code == loword)
-        return found->cid;
-    } else {
-      ASSERT(pMap->m_WordMapType == FXCMAP_CMap::Range);
-      const auto* begin = reinterpret_cast<const RangeCmap*>(pMap->m_pWordMap);
-      const auto* end = begin + pMap->m_WordCount;
-      const auto* found = std::lower_bound(
-          begin, end, loword, [](const RangeCmap& element, uint16_t code) {
-            return element.high < code;
-          });
-      if (found != end && loword >= found->low && loword <= found->high)
-        return found->cid + loword - found->low;
+  while (pMap && pMap->m_pWordMap) {
+    switch (pMap->m_WordMapType) {
+      case FXCMAP_CMap::Single: {
+        const auto* begin =
+            reinterpret_cast<const SingleCmap*>(pMap->m_pWordMap);
+        const auto* end = begin + pMap->m_WordCount;
+        const auto* found = std::lower_bound(
+            begin, end, loword, [](const SingleCmap& element, uint16_t code) {
+              return element.code < code;
+            });
+        if (found != end && found->code == loword)
+          return found->cid;
+        break;
+      }
+      case FXCMAP_CMap::Range: {
+        const auto* begin =
+            reinterpret_cast<const RangeCmap*>(pMap->m_pWordMap);
+        const auto* end = begin + pMap->m_WordCount;
+        const auto* found = std::lower_bound(
+            begin, end, loword, [](const RangeCmap& element, uint16_t code) {
+              return element.high < code;
+            });
+        if (found != end && loword >= found->low && loword <= found->high)
+          return found->cid + loword - found->low;
+        break;
+      }
+      default: {
+        NOTREACHED();
+        break;
+      }
     }
     pMap = FindNextCMap(pMap);
   }
+
   return 0;
 }
 
@@ -110,22 +119,31 @@ uint32_t FPDFAPI_CharCodeFromCID(const FXCMAP_CMap* pMap, uint16_t cid) {
   // second while loop.)
   ASSERT(pMap);
   while (pMap) {
-    if (pMap->m_WordMapType == FXCMAP_CMap::Single) {
-      const auto* pCur = reinterpret_cast<const SingleCmap*>(pMap->m_pWordMap);
-      const auto* pEnd = pCur + pMap->m_WordCount;
-      while (pCur < pEnd) {
-        if (pCur->cid == cid)
-          return pCur->code;
-        ++pCur;
+    switch (pMap->m_WordMapType) {
+      case FXCMAP_CMap::Single: {
+        const auto* pCur =
+            reinterpret_cast<const SingleCmap*>(pMap->m_pWordMap);
+        const auto* pEnd = pCur + pMap->m_WordCount;
+        while (pCur < pEnd) {
+          if (pCur->cid == cid)
+            return pCur->code;
+          ++pCur;
+        }
+        break;
+      }
+      case FXCMAP_CMap::Range: {
+        const auto* pCur = reinterpret_cast<const RangeCmap*>(pMap->m_pWordMap);
+        const auto* pEnd = pCur + pMap->m_WordCount;
+        while (pCur < pEnd) {
+          if (cid >= pCur->cid && cid <= pCur->cid + pCur->high - pCur->low)
+            return pCur->low + cid - pCur->cid;
+          ++pCur;
+        }
+        break;
       }
-    } else {
-      ASSERT(pMap->m_WordMapType == FXCMAP_CMap::Range);
-      const auto* pCur = reinterpret_cast<const RangeCmap*>(pMap->m_pWordMap);
-      const auto* pEnd = pCur + pMap->m_WordCount;
-      while (pCur < pEnd) {
-        if (cid >= pCur->cid && cid <= pCur->cid + pCur->high - pCur->low)
-          return pCur->low + cid - pCur->cid;
-        ++pCur;
+      default: {
+        NOTREACHED();
+        break;
       }
     }
     pMap = FindNextCMap(pMap);
diff --git a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
index 9693bc48ff..e2fa801a58 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
+++ b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
@@ -264,13 +264,20 @@ const CPDF_ContentMark* CPDF_PageContentGenerator::ProcessContentMarks(
     }
 
     // If there are parameters, write properties, direct or indirect.
-    if (item->GetParamType() == CPDF_ContentMarkItem::DirectDict) {
-      CPDF_StringArchiveStream archive_stream(buf);
-      item->GetParam()->WriteTo(&archive_stream, nullptr);
-      *buf << " ";
-    } else {
-      ASSERT(item->GetParamType() == CPDF_ContentMarkItem::PropertiesDict);
-      *buf << "/" << item->GetPropertyName() << " ";
+    switch (item->GetParamType()) {
+      case CPDF_ContentMarkItem::DirectDict: {
+        CPDF_StringArchiveStream archive_stream(buf);
+        item->GetParam()->WriteTo(&archive_stream, nullptr);
+        *buf << " ";
+        break;
+      }
+      case CPDF_ContentMarkItem::PropertiesDict: {
+        *buf << "/" << item->GetPropertyName() << " ";
+        break;
+      }
+      default:
+        NOTREACHED();
+        break;
     }
 
     // Write BDC (begin dictionary content) operator.
diff --git a/core/fxcodec/codec/fx_codec_flate.cpp b/core/fxcodec/codec/fx_codec_flate.cpp
index eb68cedda5..39d27a4955 100644
--- a/core/fxcodec/codec/fx_codec_flate.cpp
+++ b/core/fxcodec/codec/fx_codec_flate.cpp
@@ -709,16 +709,21 @@ uint8_t* CCodec_FlatePredictorScanlineDecoder::v_GetNextLine() {
 }
 
 void CCodec_FlatePredictorScanlineDecoder::GetNextLineWithPredictedPitch() {
-  if (m_Predictor == PredictorType::kPng) {
-    FlateOutput(m_pFlate.get(), m_pPredictRaw, m_PredictPitch + 1);
-    PNG_PredictLine(m_pScanline.get(), m_pPredictRaw, m_pLastLine,
-                    m_BitsPerComponent, m_Colors, m_Columns);
-    memcpy(m_pLastLine, m_pScanline.get(), m_PredictPitch);
-  } else {
-    ASSERT(m_Predictor == PredictorType::kFlate);
-    FlateOutput(m_pFlate.get(), m_pScanline.get(), m_Pitch);
-    TIFF_PredictLine(m_pScanline.get(), m_PredictPitch, m_bpc, m_nComps,
-                     m_OutputWidth);
+  switch (m_Predictor) {
+    case PredictorType::kPng:
+      FlateOutput(m_pFlate.get(), m_pPredictRaw, m_PredictPitch + 1);
+      PNG_PredictLine(m_pScanline.get(), m_pPredictRaw, m_pLastLine,
+                      m_BitsPerComponent, m_Colors, m_Columns);
+      memcpy(m_pLastLine, m_pScanline.get(), m_PredictPitch);
+      break;
+    case PredictorType::kFlate:
+      FlateOutput(m_pFlate.get(), m_pScanline.get(), m_Pitch);
+      TIFF_PredictLine(m_pScanline.get(), m_PredictPitch, m_bpc, m_nComps,
+                       m_OutputWidth);
+      break;
+    default:
+      NOTREACHED();
+      break;
   }
 }
 
@@ -732,16 +737,21 @@ void CCodec_FlatePredictorScanlineDecoder::GetNextLineWithoutPredictedPitch() {
     bytes_to_go -= read_leftover;
   }
   while (bytes_to_go) {
-    if (m_Predictor == PredictorType::kPng) {
-      FlateOutput(m_pFlate.get(), m_pPredictRaw, m_PredictPitch + 1);
-      PNG_PredictLine(m_pPredictBuffer, m_pPredictRaw, m_pLastLine,
-                      m_BitsPerComponent, m_Colors, m_Columns);
-      memcpy(m_pLastLine, m_pPredictBuffer, m_PredictPitch);
-    } else {
-      ASSERT(m_Predictor == PredictorType::kFlate);
-      FlateOutput(m_pFlate.get(), m_pPredictBuffer, m_PredictPitch);
-      TIFF_PredictLine(m_pPredictBuffer, m_PredictPitch, m_BitsPerComponent,
-                       m_Colors, m_Columns);
+    switch (m_Predictor) {
+      case PredictorType::kPng:
+        FlateOutput(m_pFlate.get(), m_pPredictRaw, m_PredictPitch + 1);
+        PNG_PredictLine(m_pPredictBuffer, m_pPredictRaw, m_pLastLine,
+                        m_BitsPerComponent, m_Colors, m_Columns);
+        memcpy(m_pLastLine, m_pPredictBuffer, m_PredictPitch);
+        break;
+      case PredictorType::kFlate:
+        FlateOutput(m_pFlate.get(), m_pPredictBuffer, m_PredictPitch);
+        TIFF_PredictLine(m_pPredictBuffer, m_PredictPitch, m_BitsPerComponent,
+                         m_Colors, m_Columns);
+        break;
+      default:
+        NOTREACHED();
+        break;
     }
     size_t read_bytes =
         m_PredictPitch > bytes_to_go ? bytes_to_go : m_PredictPitch;
@@ -807,17 +817,22 @@ uint32_t CCodec_FlateModule::FlateOrLZWDecode(bool bLZW,
     FlateUncompress(pdfium::make_span(src_buf, src_size), estimated_size,
                     *dest_buf, *dest_size, offset);
   }
-  if (predictor_type == PredictorType::kNone)
-    return offset;
 
-  bool ret;
-  if (predictor_type == PredictorType::kPng) {
-    ret =
-        PNG_Predictor(*dest_buf, *dest_size, Colors, BitsPerComponent, Columns);
-  } else {
-    ASSERT(predictor_type == PredictorType::kFlate);
-    ret = TIFF_Predictor(*dest_buf, *dest_size, Colors, BitsPerComponent,
-                         Columns);
+  bool ret = false;
+  switch (predictor_type) {
+    case PredictorType::kNone:
+      return offset;
+    case PredictorType::kPng:
+      ret = PNG_Predictor(*dest_buf, *dest_size, Colors, BitsPerComponent,
+                          Columns);
+      break;
+    case PredictorType::kFlate:
+      ret = TIFF_Predictor(*dest_buf, *dest_size, Colors, BitsPerComponent,
+                           Columns);
+      break;
+    default:
+      NOTREACHED();
+      break;
   }
   return ret ? offset : FX_INVALID_OFFSET;
 }